Computer networks are made up of a group of computers or devices. Each computer requires a unique address in order to know where to send data to. When a letter is sent in the post it will contain the name of the person, the house number and the area they are located in. This is the same when data is sent over the internet. An example of an address looks like this.

192.168.100.1

This type of internet addressing is called IPv4 and stands for Internet Protocol Version 4. The problem with IPV4 has become clear since more and more devices are being connected to the internet. Each device that connects to the internet needs an address and IPv4 has a finite amount of addresses available. The answer to this was to create a new version called IPv6 which allows for more devices to be connected. An example of IPv6 looks like this.

2001:0db8:85a3:0042:0000:8a2e:0370:7334



A network consists of client computers and servers each having a unique internet address. Clients will request information from the server and the server returns this information. When you are visiting a web site your web browser is the client and the web site host is the server. When a client asks the server for this information it is called a client request.

Raspberry Pi Networking

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Servers listen for client requests using a port. A port is like a door waiting for someone to knock on it. When it receives a request from a client the server will respond with the information. Each port has a number which determines the type of data to be sent. Some ports are reserved so that when a client sends a request for information, it always uses the same port number. For example when you enter an address into your Raspberry Pis web browser, it will use port 80 which is reserved for delivering web pages. The browser takes care of which port number to use so that you dont have to concern yourself with this.

If you are using a Debian based distribution or the Raspberry Shake distribution then you can view the following file which lists your network interfaces.

sudo cat /etc/network/interfaces

Network interfaces connect your Raspberry Pi to a network using a wired connection or a wireless device. A snippet of the file looks like this.

iface eth0 inet dhcp

The word iface is referring to the interface and in the case of the Raspberry Pi, this is called eth0. Eth0 is the only interface on the Raspberry Pi unless you have added any other devices. The rest of the line uses something called DHCP. This will automatically obtain a unique IP address which allows your Raspberry Pi to be connected to a network.